含金属Mg相的Mg_(2)(Sn,Si)薄膜的微观结构与热电性能

Microstructure and thermoelectric properties of Mg_(2)(Sn,Si)films containing metal Mg phase

利用高真空磁控溅射设备,采用Mg-Sn-Si合金靶材和纯Mg靶进行顺序沉积,在表面含有500 nm厚氧化硅的单晶Si(100)衬底上制备了不同Mg含量的Mg-Sn-Si薄膜。沉积Mg-Sn-Si薄膜的相组成、化学成分、表面和横截面形貌和热电性能被系统的测量、观察和分析。结果表明,制备的Mg-Sn-Si薄膜由Mg_(2)(Sn,Si)固溶体和金属Mg相组成。随着金属Mg相含量的增多,沉积薄膜载流子浓度升高,迁移率降低。沉积薄膜的电导率随着金属Mg相含量的增多而增大,而Seebeck系数降低。沉积薄膜的金属Mg相含量增加,虽然电导率增加,但因Seebeck系数急剧下降,最终导致功率因子下降。在所研究的金属Mg含量范围内,Mg_(2)(Sn,Si)固溶体薄膜含有部分金属Mg相,对提高复合薄膜的功率因子是不利的。

Mg-Sn-Si films with different metal Mg contents were prepared on single crystal Si(100)substrate containing 500 nm thick silicon oxide by alternately sputtering using Mg-Sn-Si alloy target and pure Mg target,respectively.The phase composition,chemical composition,surface and cross section morphology and thermoelectric properties of the deposited Mg-Sn-Si films were systematically measured,observed and analyzed.The results show that the prepared Mg-Sn-Si film consists of Mg_(2)(Sn,Si)solid solution and metal Mg phase.With the increase of metal Mg phase content in deposited films,the carrier concentration increases and the mobility decreases at room temperature.With increasing metal Mg phase content in deposited films,the electrical conductivity increases and the Seebeck coefficient decreases in the range of measured temperature.The power factor decreases with increasing metal Mg phase content due to rapidly decreasing of the Seebeck coefficient even if the electrical conductivity increases.In the range of the metal Mg content in the work,it is unfavorable to improve the power factor that Mg_(2)(Sn,Si)solid solution films contain some metal Mg phase.